Does anyone know of a U.S. made master cylinder kit that contains the secondary piston and who sells it? Also, the GM part number for the secondary piston alone? It is for my 1968 manual brakes drum/drum Delco Moraine master cylinder with a 1" bore. Thanks, Joe.

I have a NOS GM kit I bought in 1988 and didn't realize it was for a 1" bore and not the 1 1/8" that I needed.It's a complete kit P/N 5468453. Not sure if it will fit your application so you will need to check if interested.

I do know that NOBODY sells the secondary piston for the 1-1/8" bore MC. Not part of any kit, not available by itself either. I know I tried. My MC was original and I wanted to keep it. The solution was to buy a brand new cheapo master cylinder and take the guts out to put in my original re-sleeved core. You may need to consider that route if you can't find one for your 1" bore setup. It is surprizingly inexpensive that way. Just throw the left over casting in the trash.

Your suggestion is a good one except that in my case I also require both sets of check valves as my car has a drum/drum braking system.My research shows that GM supplies the primary piston only in the kit and the secondary piston only separately under part number 5452694.